1. Field of the Invention
The present invention relates to a control apparatus for assembling parts, more particularly to a control apparatus for assembling the parts in which an indication card for assembly on which a plurality of apertures indicating information code are provided, is conveyed together with the parts which are to be assembled in order together along an assembly line and the information code on the indication card is read to output an information regarding to the parts to be assembled.
2. Description of Related Art
In an assembly line of a motor vehicle, for example, different kinds of parts regrading to different types of motor vehicle are conveyed along a single assembly line where different parts are assembled by the worker. It is necessary for the worker to be appropriately indicated as to which parts he should select to assemble the parts. No indication as to the selection of the parts causes the worker to fail to properly assemble the parts.
Therefore, there has been proposed a control apparatus for assembling the parts in which an indication card for assembly on which a plurality of apertures are provided to represent an information code which is read to output an indication information, is conveyed together with the parts on the assembly line.
FIG. 10 shows one example of the proposed control apparatus comprising a reader 3 having a group of photodetectors and installed along an assembly conveyor (not shown) conveying several kinds of parts together with the indication card 1, and processing unit 5 processing outputs from the group of photodetectors to output an indication information useful for the selection of the parts. When the indication card 1 passes through the reader 3 and reaches a predetermined reading position where the information code of the indication card is read, the processing unit 5 decodes the outputs from the group of the photodetectors to output the indication signal to one of lamps 9A-9D of a parts receptacle 7.
Referring to FIG. 11, the indication card 1 has apertures 10 and 11 for the confirmation of the reading position of the indication card 1, apertures 12a, 12d, 12e, 12g and 12i representing the information code and an aperture 13 for parity check. The information code includes an information as to which parts the worker should select. For example, the apertures 12a, 12d, 12e, 12g and 12i represent information code "135". In this case, the aperture 13 is used to cause the number of apertures representing the information code and for parity check to be even in total. Along a passage of the reader 3 through which the indication card 1 passes, there are provided sensors 14a, 14b and 14c for the confirmation of the reading position of the indication card, sensors 15a-15i for reading of the information code of the indication card, and a sensor 16 for checking of parity. When the sensors 14a and 14c receive lights passing through the apertures 10 and 11 and the sensor 14b does not receive a light emitted from light emitting element of the sensor 14b, the position of the indication card is detected to be at the reading position.
Then the outputs of the sensors 15a-15i are taken by the processing unit 5 to read the information code of the indication card 1. Assuming that the information code "135" indicates an information as to the parts stored in a box 7B of the parts receptacle 7, the lamp 9B is turned on when the information code "135" is read by the processing unit 5. This causes the worker to easily access the parts to be assembled in the box 7B.
However, the control apparatus as shown in FIGS. 10 and 11 may produce an erroneous information when the indication card 1 passes through the reader 3 while being inclined. Referring to FIG. 12, in this apparatus, whenever the lights passing through the apertures 10 and 11 are received by the light receiving element of the sensors 14a and 14c and no light is received by the light receiving element of the sensor 14b, the indication card 1 is detected to be at the proper reading position for reading of the information code of the indication card which is inclined on the reading passage of the reader 3. In FIG. 12, the sensors 15a, 15d, 15e, 15g and 15i by which respective lights passing through the corresponding apertures 12a, 12d, 12e, 12g and 12i should be received do not always receive the respective lights even when the indication card 1 is detected to be at the reading position.